With the market requirements for projection brightness, color saturation, service life, non-toxic environmental protection, etc of projection apparatus, the types of light sources used in the projection apparatus are divided to UHP lamp, light emitting diode (LED) and laser diode (LD).
At present, the cost of high-brightness red laser diodes and green laser diodes is too high. In order to reduce the cost, a blue laser diode is used to excite the phosphor powder on the phosphor wheel to generate yellow light and green light. The desired red light is filtered out of the yellow light by a filter wheel. Together with the blue light emitted by the blue laser diode, the three primary colors of red, green and blue required for the projection image are generated.
The phosphor wheel is an extremely important component in the current projection apparatus using a blue laser diode as a light source. The blue light emitted by the blue laser diode is irradiated to the phosphor wheel to convert the blue laser into yellow light and green light, and the blue laser is reflected or passing through. In the known technology, the blue laser beam needs an additional optical path loop, but such a design makes the system not easy have a compact size and costly. The timing of the color light is fixed when designing the phosphor wheel and the filter wheel, and the illumination system cannot adjust the proportion of color mixing in the subsequent use.
The information disclosed in this “BACKGROUND OF THE INVENTION” section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in this “BACKGROUND OF THE INVENTION” section does not mean that one or more problems to be solved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art.